Most cloud providers have some kind of firewall that allows to configure a resource being accessible only from certain IP addresses. Worth it to set to your home IP address, as long as it’s static.

Tbh there also was iPod Touch, which did everything iPhone did except making calls.

Out of recommendations given here I’d ignore Arch/Manjaro, for a server you want something that you can set up and forget about and not explode when you try to update the packages after not doing so for 3 months.
Kubernetes and the likes are a bit of an overkill unless you’re planning to expand to having multiple machines or want a learning experience.
I’d recommend docker compose or podman, you generally don’t want bare bones docker as running your containers via docker run sucks ass.

Multiselect lists are outdated design, requiring prior knowledge of what they are and the use of keyboard (that you might not have if using a touchscreen device) for a simple interaction with a webpage is terrible UX. The issue is that it’s how browsers render them by default, a ‘proper’ multiselect requires a bunch of css and javascript.